Beryl the Genstone of Many Colors

Beryl crystals from Pakistan var. aquamarine
Photo by Gia Cassa

As a mineral beryl is beryllium aluminum cyclosilicate possessing the chemical formula Be₃Al₂(SiO₃)_6­.   As a gem it comes in many colors although pure beryl is colorless of the variety goshenite named after the town of Goshen in the central Berkshires of Massachusetts its type locality.  It is tinted by different colors causing it to be colored blue, green, red, yellow and white.  This is a mineral that is usually found in pegmatites although it is often found in biotite schists and in intruded limestone.  A rare occurrence is found in Utah called bixbite that has been colored red by manganese as an impurity.  Other gems in this family include aquamarine, emerald, green beryl, heliodor and morganite. 

An emerald crystal from Colombia
Photo by Gery Parent

Aquamarine is the color of sea water a bluish green with green beryl as a sub-order of aquamarine.  Emerald of course is bright green that is usually found in heavily intruded limestone although some occurrences are in biotite schist.  Heliodor is the yellow variety of beryl that is sometimes galled “golden beryl.”  Morganite is sometimes found associated with both aquamarine and golden beryl, bit is differentiated by its pink color.  Red beryl is also called bixbite or red emerald because of its red coloration.  Of all the beryl’s bixbite is the rarest, but only occurs in small crystals allowing gems cut from it to be lass then 5 carets in weight,

Golden beryl or heliodor
unknown

Beryl aside from its use as a gem is also the ore of beryllium where it occurs in granitic pegmatites.  One such crystal was a giant that occurred in the Bumpus Quarry in Albany, Maine that was about 5.5 meters long by 1.2 meters in diameter that weighed around 18 metric tons.  The largest crystal of any kind of mineral was found in Madagascar is a beryl crystal that was 18 meters long by 3.5 meters in diameter.  That is the size as the boiler on a steam locomotive.

A crystal of red beryl var. bixbite from Utah
Photo by Rob Lavinsky

Beryl is found on all the continents wherever crystalline igneous or metamorphic rocks are found.  The gems are found in the core of pegmatites where at times terminated crystals are found growing into cavities or vugs in the rock.  Some beryl like the emeralds found in Columbia are found in a peculiar black limestone that has been intruded with granite that contain in addition to the beryl an abundant amount of pyrite that certainly predates the formation of the emerald crystals.. Beryl is also found associated with biotite schist.   Many of the emeralds found in the Ural Mountains of Russia are this type of deposit.  The emeralds found at the Crabtree Corners deposit in North Carolina are also an example of this kind of deposit.

A crystal of morganite on albite and quartz.
Photo by Rob Lavinsky

One of the most important deposits of aquamarine in the United States is found in the Maryall district of New Milford, Connecticut where they occur in a large pegmatite that that was originally mined for feldspar and mica.  This mine has produced some fine specimens of both aquamarine and heliodor beryl including a 44 carat heart on display in the American Museum of Natural History in New York City.  It is also known to produce many other minerals especially large garnets and uranium minerals.  

Aquamarine as a Gemstone

Aquamarine is a member of the beryl family of gemstones that is usually colored various shades of blue/green or may appear as either light green or even as dark blue stones rivaling sapphire in color.  The mineral is a beryllium aluminum cyclosilicate with the formula Be₃Al₂(SiO₃)₆.  Terminated crystals of beryl are relatively rare, but are known to occur.  The stone has a value as a gemstone, and is a common ore of the metal beryllium.  In the case of aquamarine a small amount of iron that causes crystal defects in the crystal is the cause of its color.  The mineral beryl because of impurities in the crystal does occur in several different colors including green blue, yellow, red and white.

Aquamarine in a matrix of feldspar crystals.and other minerals including schorl the black crystal in the middle of the specimen.
Photo by Rob Lavinsky

The colors of aquamarine can range from light blue like that of the sky to a deep blue of the sea.  The darker the color the higher the price some aquamarines can sell for as much as $2,000 per caret although lighter stones only fetch a few dollars per carat.  The stone itself is fascinatingly beautiful with much appeal to women all over the world because it can complement or eye color.  For creative gemstone cutters it is an inspiration because of its ability to be cut in so many designs and still keep its beauty.

A water etched crystal of aquamarine from Brazil
Photo by Rob Lavinsky

Aquamarine is epitomized by its blue color, and the deeper blue the color the more expensive the stone making it one of the most popular stones rivaling at times its more expensive cousin emerald that also belongs to the beryl family.  The stone is hard enough at Mohs hardness of 7.5 to 8 so it can be used in most types of jewelry making it almost as popular as the classic stones emerald, ruby and sapphire.  In reality aquamarine is related to the emerald, but unlike its more famous cousin it usually free of flaws.  One flaw that is sometimes seen in aquamarine is long thin tubes that sometimes lend to its beauty in the form of chatoyancy forming tiger eyes or more rarely a star stone much like star sapphire.  Both forms of the stone command very high prices.

An example of a pear shaped aquamarine faceted gem.
Photographer Unknown

The color of aquamarine is caused by ions of iron causing crystal defects in the mineral beryl that is normally clear that is called goshenite my mineralogists because its type locality is in Goshen, Massachusetts were it is found in lithium bearing pegmatites.  Aquamarine can range from a pale blue to a strongly colored sea blue.  In some aquamarines you can see a light greenish simmer that is a typical feature of the stone.  Thee most prized color however is a pure clear blue transparent stone bringing out the transparency and shine of this magnificent stone.

Announcing a new beryl locality in South America

Nick's blue aquamarine

Photo by Nick

We just made a major find of beryl gemstones in South America.  So far the locality has produced translucent rough capable of making the most beautiful blue cabochons you have ever seen.  The rough was removed from a single crystal several meters long is a beautiful blue resembling some turquoise.  We haven’t priced this rough while we are evaluating it, but you can get further information as soon as we develop it from John Carter at: geotekllc@gmail.com 

Gemstone Occurrences in Rhode Island

This is an amethyst scepter like those found at Diamond Hill
Photo by Rob Lavinsky

There is a greenish mica schist found in Warwick that has embedded in it red almandine garnets. In East Warwick you can find purple almandine garnets embedded in a silvery mica schist. Jamestown has staurolite crystals embedded in phyllite. Garnet-staurolite bearing schist can also be found under the Jamestown Bridge,

A discovery of beryl was recently reported in the magazine Rock and Gem on the western side of Narragansett Bay in the vicinity of the Jamestown Bridge in the pegmatites found in the area. It was also found at the end of the Cliffwalk in Newport.  The largest crystal found in Newport was about 6 cm in length and 1 cm in diameter along with several other smaller specimens.

There have been moonstones reported on the beaches of Rhode Island that continue into eastern Connecticut.  One of the beaches in Rhode Island is actually called Moonstone Beach.

The state stone is bowenite a variety of serpentine of the sub variety antigorite that has often been classified as a semi-precious stone that is cut into polished slabs or cabochons.  The Maoris of New Zealand have also used bowenite to make axes.  This stone is associated with limestone and was originally found in Lincoln.

Amethyst has been from several localities in Rhode Island notably however from Diamond Hill in Ashaway, Hopkinton in Washington County.  This mineral is accompanied by several other varieties of quarts.  At times the amethyst from this locality is found as rare scepter specimens.

A variety of Jasper veined with chalcedony is found in several localities in Cumberland, Providence County.  Chalcedony has also been found at the Conklin Quarry in Lincoln and another locality is Diamond Hill in Ashaway.  

A list of the Gemstones found in Pegmatites

Triphylite found in a cavity in pegmatite in Newry, Maine. This is a rare gemstone
Photo by Rob Lavinsky

The most common gemstones found in pegmatites are beryl, topaz and tourmaline according to the experts there are over 100 other minerals that are found in pegmatites that are used as gemstones. The following list is of some of the many other gemstones that are found in pegmatites. Finding all the gemstones listed here will probably keep you busy for the rest of your life.

The other gemstones found in pegmatites

Name              Color               Mineral           Abundance      Pegmatite Type

achroite            c                      tourmaline        rare                  LCT

albite                g                      feldspar            common           NYF & LCT

amazonite         g                      feldspar            common           NYF > LCT    

amblygonite      y – c                amblygonite      rare                  LCT

aquamarine       b-g                  beryl                 common           LCT

beryllonite         c, pl & y         beryllonite         very rare           LCT

brazilianite        y-g                  brazilianite         very rare           LCT

chrysoberyl       g – y               chrysoberyl        very rare           LCT

danburite          c, y                  danburite            rare                  LCT

elbaite              c, p, g, b           tourmaline         common           LCT

euclase             b – g                euclase               very rare           LCT

fluoapatite         b, p, pur, g      apatite                common           NYF < LCT

goshenite          c                      beryl                  common           NYF < LCT    

hambergite        c, pl, y             hambergite        very rare           NYF & LCT

heliodor            y                      beryl                  rare                  NYF & LCT

hiddenite           g – y                 spodumene       very rare           LCT

hydroxlherderite  c, pl, y, b       hydroxyl “         very rare           LCT

indicolite           bl                     tourmaline         common           LCT

jeremejevite      b                      jeremejevite        very rare          LCT

kunzite              p                      beryl                   rare                 LCT

lazulite              b                      lazulite                rare                 LCT

lepidolite           pur – p             mica                 common           LCT

liddicoatite        p – r                 tourmaline        very rare           LCT

londonite          y – c                 londonite          very rare           LCT

manganotantalite  r                    m-tantalite        very rare           LCT

microlite           y, c-br              microlite            rare                  LCT

montebrasite     c, pl, p-y          montebrasite      rare                  LCT

morganite         p – o                beryl                  rare                  LCT

oligoclase         c                      plagioclase        common           NYF & LCT

petalite             c                      petalite               rare                  LCT

pezzottaite        r                       beryl                 very rare           LCT

phenakite          c, p, y               phenekite          rare                  LCT

pollucite            c                      Pollucite           rare                  LCT

quartz               c, p, sm, pur     quartz               common          NYF & LCT

rhodozite          y-c                   rhodozite          very rare           LCT

rossmanite        p-r, c, g            tourmaline        very rare           LCT

rubelite p-c                               tourmailine       very rare           LCT

sanidine            y, c                   feldspar           common           LCT

simpsonite        y, o                  simpsonite        very rare           LCT

spessertine        o                      garnet               common           LCT

spodumene       c-g                   spodumene       common           LCT

stibiotantalite     y                     stibiotantalite     very rare          LCT

topaz                b-c-p                topaz                 common          NYF & LCT

triplite               r, br, p             triplite               common          NYF

triphyllite           b-g                 triphyllite           rare                  LCT

verdelite           g                      tourmaline         rare                  LCT

zircon               c, p, br, g         zircon                common          NYF & LCT

Abbreviations: c, colorless; g, green; y, yellow; b, blue; p, pink; r, red; o, orange;

br, brown; pur, purple; sm, smokey; pl, pale.

After V.B. Simmons Gem bearing Pegmatites in Geology of Gem Deposits, Editor Lee A. Groat, Yukon Geological Survey

This list is incomplete, but they are always finding new minerals in pegmatites and some of them are gemstones. Some of them are so rare that only one example is known. The hunt goes on!